Assessment of Structural Integrity and Potential Improvements of Micro Hydropower Turbine
A comparative study of two different hydro power turbine designs, made
by Remote Hydrolight (RHL) was conducted. The shaft of the first design
has suffered from fatigue failures and a bushing was introduced to solve
the problem, giving the second design.
In this thesis, flow calculations, finite element analysis (FEA), inspection
of micro structures and the weld were carried out, along with fatigue life
calculations. This was done for both designs to compare the existing
fatigue data with the findings. It was found that the introduction of the
bushing is generally beneficial. The stresses at the weld toe previously
subject to fatigue fracture were reduced by at least 52,5%.
Two kinds of laboratory activities were carried out in this thesis. Firstly, a
metallurgic analysis was performed and unveiled flaws on and in the weld.
Micro cracks, cavities and general porosity suggested that the welding
procedure also needs to be revised. Such cavities, especially if occurring
at the weld toe of the outer rotor disk, may lead to fatigue failure, despite
the introduction of the bushing. In addition, a micro Vickers hardness
test was conducted. The tests showed that a range of materials are used
for making the turbine, with the shaft material having the highest tensile
There exists too few fatigue data?s for establishing a fatigue stress limit for
the different components. Based on the data received, no reliable fatigue
life for the modified turbine with bushing can be calculated.
Place, publisher, year, edition, pages
Institutt for produktutvikling og materialer , 2013. , 108 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-22225Local ID: ntnudaim:9982OAI: oai:DiVA.org:ntnu-22225DiVA: diva2:648680
Haugen, Bjørn, Førsteamanuensis